From: Keith Busch <kbusch@kernel.org>
Date: Thu, 21 May 2020 02:22:53 +0000 (-0700)
Subject: nvme: set dma alignment to qword
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3b2a1ebceba3e03b17ef0970bb7757a3a64cdc8b;p=linux.git

nvme: set dma alignment to qword

The default dma alignment mask is 511, which is much larger than any nvme
controller requires. NVMe controllers accept qword aligned DMA addresses,
so set the request_queue constraints to that. This can help avoid bounce
buffers on user passthrough commands.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a3a4dbc59af18..569671e264b50 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2322,6 +2322,7 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
 		blk_queue_max_segments(q, min_t(u32, max_segments, USHRT_MAX));
 	}
 	blk_queue_virt_boundary(q, ctrl->page_size - 1);
+	blk_queue_dma_alignment(q, 7);
 	if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
 		vwc = true;
 	blk_queue_write_cache(q, vwc, vwc);